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Pop III, Gravity Waves and 6 Li … oh my!

Pop III, Gravity Waves and 6 Li … oh my!. Michael Rutkowski Journal Club 7 . 9 . 2007. Notes. Definition of z:. Lepp and Stancil (1998), adapted partially from Peebles (1993). Notes. Initial Mass Function Generally, a power law describing the distribution of mass Populations of Stars

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Pop III, Gravity Waves and 6 Li … oh my!

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  1. Pop III, Gravity Waves and 6Li … oh my! Michael Rutkowski Journal Club 7 . 9 . 2007

  2. Notes • Definition of z: Lepp and Stancil (1998), adapted partially from Peebles (1993)

  3. Notes • Initial Mass Function • Generally, a power law describing the distribution of mass • Populations of Stars • Pop. I – the Sun, metal rich, in the plane of the galaxy • Pop. II – metal poor, in globular clusters • Pop. III – no metals, minihalos? Cosmic rays • relativistic protons, alpha-particles ejected from almost every energetic object in the universe Bruzual and Charlot, 1993

  4. Gravitational wave background from Population III black hole formation Jose C.N. de Araujo Oswaldo D. Miranda Odylio D. Aguiar Instituto Nacional de Pesquisas Espaciais

  5. Gravitational Waves • What are they? • Think GR (which I’ve never had) • Gravity can be expressed as the curvature of space time • A changing mass distribution can create ripples in space-time which propogate away at the speed of light. • No detection YET… but indirect influence has been measured in the binary neutron star system PSR1913+16

  6. Gravitational Waves • Where are they generated? • SNe, collapsing stars to form black holes, coalesence of compact binaries, rotating neutron stars, cosmic strings etc etc… etc…. • Araujo et. al. consider only the waves generated during core collapse of Population III stars to black holes

  7. Gravitational Wave Production-Formalism • GWs are characterized by their dimensionless amplitude and frequency • Spectral Density: • For the AST531 folks: This not what we did on the homework • Rather, it is a relationship which determines the total amount of energy emitted as GWs over the entire range of redshifts (~10 - ~50)and from progenitor masses of interest (here 25-125 MSol )

  8. Gravitational Wave Production-Formalism • Dimension Amplitude • A way to incorporate redshifts, i.e. expansion of the universe on these scales • Necessity of h • Reduces the complexity of the background flux graphs • Models are useful iff they predict the location (in “z-space”) of the Pop. III collapse

  9. Determining z • The importance • There is a non-negligible time between the generation of Pop. III stars (and their associated Stromgren spheres) and reionization • Determining ages of Pop. III will put an upper limit before which re-ionization would not have occurred.

  10. The model • Authors accept that there exist a number of variables • Efficiency of gravity wave production • IMF • Condensation of baryons in stars • Range of z during which P.III stars were produced… • Most of these variables are inherent to the problem due to lack of observables • Taking the risk: • P. III stars could be • Directly responsible for ionizing Hydrogen • Account for the metallicity found in Lyman-αForest Clouds

  11. The model Guidelines for detectors: the background amplitude

  12. Detection • LIGO I: no • LIGO II: maybe • LIGO III: “more optimistic” -To make matters worse, there could be overlap. This could occur anywhere in the bandwidth -LISA wouldn’t detect background GWs

  13. Population III Generated Cosmic Rays and the Production of 6Li Emmanuel Rollinde1 Elisabeth Vanioni1 Keith A. Olive2 2:Institut d’Astrophysique 1:U. Of Minnesota

  14. Legend has it… • 7Li from BBN, 6Li from GCRN • The bulk of Population II 7Li abundance is produced by BBN, with 10% supplied by GCRN • Basis for “Spite Plateau”s • 6Li should show strong (log-linear) correlation to Fe

  15. Survey says … • WMAP (2006) data: • Ωb * h2 ~ 0.02233 • η ~ 6.12 x 10-10 • 4.15 x 10-10 < 7Li/H < 4.97 x 10-10 • A factor of 1-2 time greater than observed abundances • Observations of 6 Li (Asplund et. al.) • [6Li]independent of metallicity. • 6Li plateau about 1000 times above the BBN predicted abundance

  16. Paper I vs. Paper 2 • Paper 1-not so realistic • 2005 • Considered initial burst of CCRs correlated to a very early generation of Population III stars at redshift zs • Paper 2-realistic • 2006 • Considered more linear (on log-linear plot) SF on log-linear

  17. Birthrates -Phi functions: both are power laws (individually normalized) with a near Salpeter slope -Psi functions: SFR rates, mediated by either: a) time for the massive component b) the metallicity of the IGM for the normal component

  18. Deathrates, Cosmic Rays • Assumptions: • Massive component: 40 < MSol < 100 • 100 MSolis the greatest mass, (Daigne et al. looked at 140-260MSol , 270-500MSol) • All stars > 8 MSol go supernova

  19. Deathrates, Cosmic Rays • Energy of Core Collapse: • Stars with mass 30-100 MSol generate black holes of mass equal to the star’s helium Helium Core Mass approximated by core (Heger et al., 2003) • Parameterization of the energy injected in cosmic rays per supernova where: epsilon = 0.01-0.3 (poorly confined)

  20. Deathrates, Cosmic Rays

  21. Deathrates, Cosmic Rays

  22. Cosmic Rays and the production of Lithium in the IGM • Difference between Paper 1 and 2 characterized well in terms of the CR energy density: • In contrast to Daigne et al., assume all CRs are ejected • Flux of alpha particles:

  23. Results(that I’m comfortable with)

  24. Results(that I’m not comfortable with) • Many observations (of quasars) set “conservative” upper limit on TIGM of 105 K • Rollinde et. al. find strong correlation between induced TIGM and CR energy cutoff

  25. Results(that I’m not comfortable with)

  26. Results(that I’m not comfortable with) • To their credit: • Model assumes epsilon = 1.0 for all z • Temperatures in the warm-hot IGM is of the same magnitude (Cen and Ostriker, 1999; Simcoe et al. 2002).

  27. Production of Lithium in ISM • Similar to production, in mathematical terms, to IGM production • But! • Structure exists • Presence of strong magnetic fields • Presence of “characteristic column density” that can/will affect epsilon

  28. Summary • Further support for the necessity of Population III • Can be used to produce the 6Li plateau • Provides some insight into mass density in old star forming regions • Model is more robust, allows for: • Reionization at z ~ 11 • Observed SFR at z </= 6

  29. Papers of Interest • Observational: • Asplund et. al. “Lithium Isotopic Abundances in Metal Poor Halo Stars” 2006 • Theoretical: • Daigne et. al. “Hierarchical Growth and Cosmic Star Formation: Enrichment, Outflows, and Supernova Rates” 2006

  30. Summaries of the two papers • Paper b) • Paper a) • Use core collapse of Pop. III stars to model the environment of the old universe • Find an upper limit to z for the reionization

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